1. Field of the Invention
The present invention pertains to an improved aircrew systems tester that includes an apparatus that accurately detects leaks for elastic items such a chemical masks accurately down to 0.5 sccm.
2. Description of the Related Art
An aircrew systems tester is a device that tests various life support equipment used in conjunction with aviation. Such life support equipment includes oxygen masks. The tester is designed to determine whether the devices are working properly, whether leaks are present, and also whether the mask fittings are acceptable.
Recently, many advances have been made in the aircrew systems tester technology. For example, aircrew systems testers have become miniaturized so that bottles of compressed gas are no longer necessary. Also, the testing unit has become integrated so that other tests, besides mask tests, can be performed by the same tester. These include anti-gravity suit testing, microphone and earphone testing, along with helmet and mask fitting and troubleshooting.
One limitation in previous aircrew system testers is that testing can be performed only up to a certain pressure. This is problematical as man mounted regulators require a higher pressure than is available in previous aircrew testers. Also, there is a need to test chemical masks, including joint service aircrew masks (JSAMs) for chemical and biological testing by a portable tester.
Another problem is that elastic items, such as nuclear, biological or chemical masks (NBC masks) are required by the military must have a mask integrity of less than 0.5 sccm (standard cubic centimeters per minute). Traditional leak detection techniques, such as pressure decay, are inadequate in being able to accurately measure leak rates of 0.5 sccm at pressures of 6 IWG (inches of water gauge). This is because leak rates in elastic bodies vary dramatically with pressure and that by having the pressure within the device under test of an elastic item change during the test will produce inaccurate results. Therefore, there is currently a need for an apparatus and a technique that can accurately measure and detect leaks of 0.5 sccm at 6 IWG accurately in such elastic bodies.